Electrically operated device for the control of fluid pressure servomotors



Sept. 4, 1951 H. TREVASKIS OF FLUID PRESSURE SERVOMOTORS Filed Dec. 51, 194.6

ELECTRICALLY OPERATED DEVICE FOR THE CONTROL 2 Sheets-Sheet l iii gen 701' H. TREVASKIS ELECTRICALLY OPERATED DEVICE FOR Sept. 4, 1951 2,566,708 THE CONTROL 0F FLUID PRESSURE SERVOMOTORS 2 Sheets-Sheet 2 Filgd Dec. 51, 1946 as k m m m H Patented Sept. 4, 1951 CGNTROL rims SURE smvm "Me'rens Henry Trevaskis; e eme -1 01B h ziiiilej ls g f l n Appliezttiorrmeeember Rulghen tish c mme t 31, emma-mm air-9.521

-In;Greatcfiritaiinmecemher 22 -1955 with 's'cime type's 'of airc ireift it isdsirilile triatj' lngth--'t5;th'e fluitl transmissionnne shqum -lye-es*sneiees-'wssible-andatnat the "pee -1' m: T WflfinW-bf the---pr@;1;1n pressure sholzl'd be w possmmaneruert rag. 1 he--pre's'ent'invention; ms tar rg ma r ob feet to p'r bvg ae animprevee eppamtuszwr eon- -frOHip'g-* j the-sliiiply-bf -fiiklidto fluid fietu a'ted lirakefioperatihg means I ich emes -the sa;id iles'idi'lta to bebhttt lned w ich additleh --is-- "sens1-nve -opei atilin--ehd which; admits er am eeuraiteeentrbl of the biaking presse're. I

Abe'orclirig -t'0 Tth'e inventionan sme ma-515pp'm ug iercenmimng u esugpiytos numxrrom 4 'e' sollrceo-f silphlyte a'elo's'ed cntainerfeoni prfses an inlet valve for permitting the-newer: fr'cnn th'e sol-irce' 6f 'stip'ply te 'the Said-container, -"1eetr6.-'magnetidmeans fob Opening L the; said valve, and. a pressure-selecting deviceriot-on5 trellfi'igf theenemy-iii eletriGblxtrent operating "the eeiid e1eetrb magnetic=-nieans whiem I said defie fs respbnsive te the fluid --pressure the gill ednteiner andmperates amtematicel-ly to cut if: the eurrent to the -saiaelectroemegnetic ens= When- -the-said pressure reaches as prefieteflnined v-alne whereby r the sa.icl 1nltya 1ve is elb'sedland the fluid supply t6 the said container i's c'u'tmff. I I I I rhe=- inventieni-a1so.-;resiaesin* the impre ie'd -".-flizid1.actuated brake eneratihg -lfimean's tome-nescribed hereinafter.

reAni-embudiment. mt; the inventiomwill. new be 31 seribeclw tti pertieular:neference-tothe Leccom enta l?stdrma ines il ie}:1 illu tre erthe immtie in its application to a fluid actuated brake operear s 1 1; the Mee i g-1whefiwteimm g .ffluj c ay-a d scr bes- 21a cill ibnlarit 1,1 ntent speen amo t 2.0 '.I 1 heid wih y yheels bffziirereft in aceercla-nee With-t e m- :afere'saidend I I I I I II A5 illustrated in the drawings, thQU PlQ-Y neeemner zz; 1965" G] glfZL- -fl brake perating means incorporates. a source X)! 2 f'lui'diiressiire 5 1 which is ineommunib'atlon by -Way b'f api e line B-with tl'i'emain inlet chamber a of at fluid. relay lwhich he's been stated already -i's-eonstriucted in accordance withthe invention described and 'elaiined-in oiir prioi British Patent 1 Sneeifleation-Nm 5665201 fniit wh'ichv-i'elayl-is bnly shown diagrammatically in a Figure- 1 s or =s'the I vpresentadrawirfls. I -10 "The 1111's: 5 has a-by-paiss bonneeti'dn-by 1 wa 01 a; pipe line :60 with Fat-chamber 8al-Whieh 45 n eommunidatfimfiwith a eh'amber 8b by way of a passage 80 cdnt'rolledbyen'eleetre-magnetiea-11y bperatedwa-lve 8, ifsaldwalyebeingrefrred 1'5 =tb fhereinaltter was the lectm magnetic inlet evfalve 8. v -lhe chamber-v81) is 1 m eomni-unieatienwith :chamber '91) whlchdn turn is in communication withthe atmosphere. by why of a passage 90 con- -=v=trd1lcl why. asecond zelectro-"mgnetically dperated waive '9,'w-h-leh will bel referred "to, hereinafter e-as- 'the'eleetr -magnetic exhaust valve: 9. 'l?he ehamberse'8b-..end "0b: areeintereonheeted -by. a passage: 1 01 which rig in communication by way .of a pipeline 2| t. with the. balancing pressure I side lb of the fluid relay 1.

1 'lihe-vvelve's 8 am S areectuated, by solenoids {7 8d 9d fespeetivelmwthiaNaive:- 8 being open i when the solenoid-Sa is energized and, conversely, -the-N aJV6 9 being-closedwherrthe solenoid. adeis energized. ":When both solenoids; are energized, "therefore,- Jv-alye 8,- isopen and valve 9 closedand fluidis supplied ;-V= when --b 0thsolenoids are .deenergized; valve &;is:clesed and'valve 9 open,;and the;system:-i's exha1u ted. -,.When solenoid 911 is 1 energizedand;;solenoidq 8d ,QQYG BGIgi Qd -bOth wakes are welosed; 11ml pressure: is; held static in .the system Both :valvesere not open :simul- -taneou'sly. 40 The sele'neidse-fldi-and' 9d".Tres-peetively of "the electro-magnetic inlet and exhaust valves =& "and flare eleetrieallyconnected, by lead 8e and 9e L'With lareuatelcontaicts l 20),; Ila-contained within a control housing;whichisformedmf twointercon- A5-. nec .l ats 1 L3 1213 endv which is --1oy ated eddaeent toetheuoperetor. Ehe contacts Mai; r21) are keshapect in emss-seetione andi have -their ll xorigontarllimbs extending towardeach other but I -,;spaa,eedu to orm a :gap whichimay-ibe spanned -by an Came-ct elisc; 514,-.- which-,- ma,y rest. and; .be supported on the opposed horizontal-limbs; lThe-eone s. e e m untee 10. @pposite sides f, a control plung r: 5 f ;;i sulat ng material and extend "..b19W=" S;: 9 Z ecen o. orm a spew whic 7 top plate of the housing I311.

I217. The plunger I is connected by means of a link I6 to a, setting lever l7 under the control of the operator. The plunger I5 is normally pressed downwardly by a coil spring Ila confined between the upper face of the plunger and the The control or setting lever I1 may be similarly moved by a spring I'Ib, Fig. 1.

The control plunger I5 has mounted therein eccentrically a vertically arranged spring I8 which is always in electrical connection with the contact disc I4 aforesaid and with the source of electric supply I 9 through a lead I911. The source of electric supply l9 also is in electrical connection with the solenoids 3d and 9d of the electromagnetic inlet and exhaust valves 8 and 9.

As will be seen from an examination of Figures 2, 3 and 4 the contact disc It can assume three positions. In Figur 2 the contact disc I4 has been pushed against thelower face of the plunger I5 and out of contact with both of the horizontal limbs'of the L section contacts 32a, 5 21) so that the circuits through both the solenoids 8d, 9d are broken. In Figure 3 the contact disc it is in con= tact with both of the horizontal'liinbs of the contacts I 2a, I2b aforesaid so that the circuits through both the solenoids 8d, 9d are completed whilst as shown in Figure 4 the contact disc M is out of con tact with the horizontal limb of +he contact lZa but is pressed by the spring I8 into contact with the horizontal limb of the contact I 2b so that the circuit through the solenoid ad is completed but the circuit through the sol noid M is broken.

The arcuate electrical contacts i211, i212 and the control plunger I5 are contained within the upper part I So of the control housing I3, the lower portion I312 of which contains a hollow pis ton 20 contained within a cylinder 530 which is in communication by way of a pipe line Zia with a pipe line 2! leading from the outlet 'lc from the fluid relay 7 to the brake applying means 22 which is of a known kind, said piston 20 being called hereinafter th pressure balancing piston 20. This pressure balancing piston 2a"; is asso ciated with a diaphragm 23 for ensuring a fluid tight operation.

Projecting from the upper side of the pressure balancing piston 29 is the lower end of a rod 24, the upper end of which is of conical formation and is disposed adjacent to the centre of the underside of the contact disc M referred to hereinbefore. Arranged around the said rod is a compression spring 25, one end of which abuts an intermediate flange I 3d within the upper part I3a of the control housing whilst the other end of the said spring 25 is disposed within and in abutment with the bottom of a recess in the upper portion of the pressure balancing piston 21!.

The spring 25 tends to force the pressure balancing piston 20 towards the closed end of the cyl inder I 30.

The electrical circuit is such that when the circuits through the solenoids 8d and 9d of the electro-magnetically operated inlet and exhaust valves '8 and 9 are completed the electro-magnetic inlet valve 8 is caused to open whilst the electromagnetic exhaust valve 8 is caused to close.

The solenoids 8d, 9d of the electro-magnetic inlet and exhaust valves 8 and 9 are continuously rated and have a current consumption of the order of 0.1 ampere per hour.

The operation of the invention is as follows:

When it is desired to carry out a braking operation the operator adjusts the setting lever I! to give the desired degree of braking pressure required and this movement of the setting lever I! through the link I6 raises the control plunger I5 in the upper part I3a of the control housing and s0 enables the contact disc I4 to make contact with both of the horizontal limbs of the L section contacts I2a, I2b. This completes the circuit through the solenoids 8d, 9d of the electromagnetic inlet and exhaust valves 8 and 9 so occasioning the electro-magnetic inlet valve 8 to open and the electro-magnetic exhaust valve 9 to close.

The opening of the electro-magnetic inlet valve 8 enables pressure from the supply 5 to pass by way of the bye-pass 6a through the chambers 8a, 8b to the balancing pressure side lb of the fluid relay 1 where it builds up pressure and causes the delivery valve of the relay to open and the exhaust valve to close so that the fluid pressure passes to the brake applying means 22.

The pressure applied to the brake applying means 22 also reacts on the pressure balancing piston 20 and moves the said piston 20 in an upward direction in the cylinder I30 in the lower portion I3b of the control housing until the upper end of the rod 24 reaches the contact disc I4, and as this disc I4 is spring loaded off centre, the said disc I4 tilts and breaks the circuit through the solenoids 8d of the electro-magnetic inlet valve 8 only, the circuit through the solenoid'Qd of the electro-magnetic exhaust valve 9 remaining completed. Consequently as the air supply is now out off, the braking pressure which has been attained can-be maintained as long as desired.

When it is required to release the brakes, the movement of the setting lever I! to the off position causes the downward movement of the control plunger I5, thereby breaking the circuit through the solenoid 9d of the electro-magnetic exhaust valve 9 which in consequence opens and releases the pressure from the fluid relay as described in the aforesaid British Patent Specification No. 560,201.

It will be understood that the operating lever I! may be set so that brakes may be applied for parking purposes.

It will be appreciated that with brake operating means as hereinbefore described the majority of the components can be built into close proximity with the brake units so that the only outside connections required are one small bore pipe 2 la leading to the control housing and three small capacity electrical leads two of which connect the contacts I211, I2b in the control housing with the solenoids 8d, 9d of the electro-magnetic inlet and exhaust valves and the other of which electrically connects the disc I4 with the source of electric supply I9.

In addition it will be appreciated that braking pressure is built up substantially instantaneously and that pressure control is accurate and sensitive.

Although the invention has been described in its application to and is intended primarily for the actuation of fluid operated aircraft brakes it is to be understood that the invention may also be applied to the actuation of fluid operated vehicle brakes and to other apparatus for controlling the supply of fluid to a closed container.

Further it will be understood that, if desired, means may be provided for mechanically connecting the control piston I5 to the rudder mechanism of the aircraft or to the steering mechanism of the vehicle so as to provide for differential operation.

Having described my invention. what I claim is:

1. Electrically operated device for the control of pressure fluid which comprises a housing, fluid relay supply and delivery conduits connected to said housing, actuating and release valves in said housing controlling the admission of fluid to, and exhaust from, said delivery conduit, a movable wall in said housing controlling said actuating and release valves and dividing said housing into a chamber communicating with said delivery conduit and a pressure balancing chamber, an electric circuit having a pair of parallel branch circuits, an electro-magnetically operated inlet valve actuated by one branch circuit to admit pressure fluid to said pressure balancing chamber, an electro-magnetically operated exhaust valve actuated by the other of said branch circuits to exhaust pressure fluid from said pressure balancing chamher, a manually movable pair of arcuate contact strips, one for each of said branch circuits and having inturned ends, a displaceable contact disc connected to a source of electric energy and spring pressed into contact with said inturned ends of said contact strips, a pressure selecting member for displacing said contact disc successively from one of said strips and then from both strips and comprising a plunger movable in the direction of manual movement of said pair of contact strips and actuated by the pressure or fluid in said delivery conduit to contact said disc at a point nearer one of said strips than the point of sprin pressure thereon and to lift said disc.

2. The device or claim 1 in which said plunger contacts the center of said disc and the spring pressure is applied eccentrically thereto.

3. Apparatus for controlling the pressure of fluid in a pressure applying system which comprises an inlet valve to said system, an exhaust valve from said system, an inlet electric circuit comprising an electro-magnet to open said inlet valve when energized, an outlet electric circuit comprising an electro-magnet to close said outlet valve when energized, and a switch movable to close both said circuits and comprising a pair of terminals, one for said inlet circuit and the other for said outlet circuit, a contact connected to a source or" electric energy spring pressed into contact with both said terminals, a progressively movable means in said system to move said contact away from said terminals against the action of said spring to move said contact first from said terminal of said inlet electric circuit and then from both said terminals.

4. The apparatus or claim 3 in which said terminals are movable toward or from said spring pressure of said contact.

5. The apparatus of claim 3 comprising a relay actuated by the pressure in said system and in which said contact is moved away from said terminals by the pressure in said relay.

6. The apparatus of claim 5 in which said terminals are movable toward or from the direction of pressure on said terminal.

7. Apparatus for controlling the pressure of fluid in a pressure-applying system which comprises an inlet valve to said system, an electromagnet to open said valve when energized, an

exhaust valve from said system, an electromagnet to close said exhaust valve when energized, an electric circuit connecting said electromagnets in parallel, a switch movable manually to close the circuit through both said electromagnets, said switch comprising a pair of terminals and a contact spring-pressed against both said terminals, and means movable progressively by increasing pressure in said pressure applying system to move said contact away from said terminals against the action of said spring and having its point of pressure off-set from said spring to move said contact first from the inlet terminal of said circuit and then from bothof said terminals.

8. The apparatus of claim 7 in which said terminals are movab'ie manually toward or from said pressure movable means.

9. Apparatus for controlling the supply of fluid under pressure in a system comprising a solenoid operated inlet valve, a solenoid operated exhaust valve, a pressure-selecting device having a manu ally operated plunger, a pair of electrical contacts in the form of strips which move with the plunger and which have inwardly turned ends, one oi said contacts being in circuit with the inlet valve solenoid and the other contact being in circuit with the exhaust valve solenoid, a device responsive to the pressure within said system and a displaceable contact make-and-break means in the form. of a disc of conductive material adapted to bridge the gap between the inwardly turned ends of said electrical contacts.

10. Apparatus of claim 9 comprising spring means located eccentrically relative to said disc, said disc being tiltable upon application of pressure to the center thereof to break contact with the electrical contact connected to the inlet valve solenoid whilst still maintaining contact with the electrical contact connected to the exhaust valve solenoid.

11. The apparatus of claim 9 comprising a projecting portion associated with said pressure responsive device to exert pressure on the disc for eiiecting a tilting or a complete lifting of the disc, depending on the movement of the plunger and the displacement of the pressure responsive device.

HENRY TREVASKIS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,496,953 Stewart June 10, 1924 1,823,225 Wright Sept. 15, 1931 1,878,822 Dewandre Sept. 20, 1932 2,091,043 Hewitt Aug. 24, 1937 2,113,621 Kershaw Apr. 12, 1938 2,170,240 Fitch Aug. 22, 1939 2,219,062 Almond Oct. 22, 1940 FOREIGN PATENTS Number Country Date 412,756 Great Britain July 5, 1934 

